When Bangkok lawyer Winyat Chatmontree was allowed to meet his client in detention at an army base in Bangkok, Pratin Chankate shuffled in blindfolded and shackled by military guards.

At their second meeting Pratin, a former police officer charged with plotting to attack senior government officials who was officially in civilian custody, was taken away after five minutes by soldiers, Winyat said.

Pratin is detained in a new facility established by the Thai junta to hold people deemed threats to national security, in what lawyers and rights groups say is an unprecedented expansion of the military's control over the criminal justice system.